Amazon's cloud services unit AWS was struggling to recover on Monday from a widespread outage that knocked out thousands of websites along with some of the world's most popular apps - Snapchat and Reddit - and disrupted businesses globally.

The turmoil marked the largest internet disruption since last year's CrowdStrike malfunction hobbled technology systems in hospitals, banks and airports, and highlights the vulnerability of the world's interconnected technologies.

After more than six hours of disruptions, some applications were gradually coming back online as of 10am ET (1400 GMT). But AWS acknowledged it was still experiencing elevated errors.

"We can confirm significant API errors and connectivity issues across multiple services ... We are investigating," AWS said in the latest update on its status page.

To aid the recovery, AWS said it was putting in place limits on the number of requests that can be made on its platform.

While some apps like Reddit and Roblox had largely stabilised, according to outage tracking website Downdetector, others, including Snapchat and Duolingo, were showing a resurgence in issues seen earlier in the day.

Issue originated from AWS site known for previous outages

AWS provides on-demand computing power, data storage and other digital services to companies, governments and individuals. Disruptions to its servers can cause outages across websites and platforms that rely on its cloud infrastructure.

AWS is the largest cloud provider in the world, followed by Microsoft's Azure and Alphabet's Google Cloud.

AWS said on its status page that Monday's outage originated at its US-EAST-1 location in northern Virginia, its oldest and largest for web services. The site suffered previous outages in 2021 and 2020.

Also Read: Snapchat, Duolingo crash! Massive AWS failure paralyses internet apps globally

Asked for comment, AWS directed Reuters to its status page. Amazon did not respond to a request for comment.

Junade Ali, a software engineer, cyber expert and Fellow at the Institution of Engineering and Technology, said the issue appeared to be with one of the networking systems AWS uses to control a database product.

"As this issue can usually be resolved centrally ... unless there are further issues identified, the issue should be able to be mitigated over the coming hours," he said.

Hours later, a rocky recovery

Ookla, which owns Downdetector, said over 4 million users reported issues due to the incident.

Snapchat, for instance, last had over 7,700 reports on Downdetector, up from about 4,000 reports earlier, but still lower than the peak of more than 22,000.

AI startup Perplexity, cryptocurrency exchange Coinbase and trading app Robinhood all experienced platform disruptions and attributed them to AWS.

Amazon's own services, including its shopping website, Prime Video and Alexa, were also hit, although Downdetector last showed a decrease in severity.

Fortnite, owned by Epic Games, along with Clash Royale and Clash of Clans were among the gaming platforms affected. Uber rival Lyft was also knocked down in the United States.

In a post on X, Signal's President Meredith Whittaker confirmed the messaging app was hit by the outage as well, though billionaire Elon Musk, who owns X, said his platform continued to work.

Outage exposes risk of dependence on handful of providers

In Britain, Lloyd Bank, Bank of Scotland and telecom service providers Vodafone and BT were also facing issues, according to Downdetector's UK website, as was UK tax, payments and customs authority HMRC's website.

The problem highlights how interconnected everyday digital services have become and how reliant they now are on a small number of global cloud providers, with one glitch causing havoc with business and day-to-day life, experts and academics said.

"The main reason for this issue is that all these big companies have relied on just one service," said Nishanth Sastry, Director of Research at the University of Surrey's Department of Computer Science.

While there has been no indication yet of a potential cyberattack behind Monday's outage, the scale of the disruption has fed speculation.

"When anything like this happens, the concern that it's a cyber incident is understandable," said Rafe Pilling, director of threat intelligence at cybersecurity firm Sophos.

"AWS has a far-reaching and intricate footprint, so any issue can cause a major upset."